Tetracyclines,Biological sources,History,Sturctures,SAR,Mechanism of action,Spectrum of activity,Important structural units and the three acidity constants in the tetracycline molucule,amphoteric nature,epimerisation, chelation with metals,toxicity and uses.

1. Prof.P.Ravisankar
Vignan pharmacy college
Vadlamudi.
Guntur Dist. Andhra Pradesh, India,
Phone: 09059994000.
Email: banuman35@gmail.copm

2. Definition:
Tetracyclines are octahydro napthacene derivatives which
are bacteriostatic and broad spectrum antibiotics that kills
certain infection- causing microorganisms and are used to
treat wide variety of infections.
Introduction:
 Tetracyclines are introduced 50 years ago as potent
broad spectrum antibiotics.
They are biosynthesized from acetic acid and propionic
acid
units in microorganisms.
Tetracyclines possess a wide specturm of acitivty i.e.
gram+ve and gram-ve bacteria.
They are mainly designed for oral route but parenteral
and topical forms are available.

3.  Classification
According to duration of action:
Short-acting (Half-life is 6-8 hrs)
Tetracycline
Chlortetracycline
Oxytetracycline
Intermediate-acting (Half-life is ~12 hrs)
Demeclocycline
Methacycline
Long-acting (Half-life is 16 hrs or more)
Doxycycline
Minocycline
Tigecycline

4. According to source:
Naturally-occurring
Tetracycline
Chlortetracycline
Oxytetracycline
Demeclocycline
Semi-synthetic
Doxycycline
Lymecycline
Meclocycline
Methacycline
Minocycline
Rolitetracycline

5. Historical background:
 In 1945 Chlortetracycline(prototype) of tetracyclines was
discovered by
Dr.Benjamin,M.Duggar,under the guidance of yellapragada subba Rao.
 He was an employee of Lederle Laboratories in U.S.A.
 Dr. Duggar produced chlortetracycline (Aureomycin) form golden –
colored soil bacterium called Streptomyces aureofaciens by
fermentation technology.
 In 1950 oxytetracycline (Terramycin) was discovered by Findalay
etal. From a similar bacterium called Streptomyces Rimosus. In 1950
Pfizer company received US patent for tetracycline.
 Later wood ward determined the structure of oxytetracycline and
made it easy to L.H Conover of Pfizer Research dept. for producing
tetracyclines as a synthetic product.
 Doxycycline, minocycline are the semi synthetic derivatives of
tetracyclines.
 In 2005 a new subgroup of tetracycline was introduced with
tigecycline as the first member.
 Because of the structural similarity tetracyclines are referred to as
close congeners of polycyclic naphthacene corboxamide.

6. Sources
 Tetracyclines are obtained from various
species of Streptomyces bacteria by
fermentation technology.
 Chlortetracyclin(aureomycin) which was
isolated in 1948 from mud-growing
microorganism called streptomyces
aureofaciens– so called because of its
golden colour.
 Oxytetracycline (Terramycin)– from
Streptomyces rimosus.
 Tetracyclines also obtained

7. Chemistry
Stereochemistry of tetracyclines is very complex.
Carbon atoms at 4,4a,5,5a,6,12a are potentically chiral depending on substitution
Methacycline ,Oxytetracycline ,Meclocycline, Doxycycline posssess 5-hydroxy
Substituent have 6 chiral corbon and others have only 5 chiral carbon atoms.
Note that the carbons that join the rings aren’t numbered and referred to as Xa,
where X is the carbon in front of the joining carbon. There is not a 6a at all

8. Chemistry
 These drugs have 5 or 6 chiral centers,
anywhere with a substituent without a
double bond can be a chiral center. If the
stereochemistry is changed, activity and
potency is changed
 Extended conjugation- if you look at the
structure as drawn, there appears to be
three acids and one base, but only 3 pKa’s.
However, due to conjugation, there are
really only two acids and one base
 These drugs are amphoteric and exist as zwitterions in solution, which decreases
solubility. The hydrochloride salt is soluble, but it will crystallize out on standing due to
zwitterion formation, therefore, excess acid must be used. The hydrochloride form is
available in capsules, and sodium or potassium salts could also be used. However, they
wouldn’t be as stable
 Copper, magnesium, aluminum, and fluorine ions chelate the tetracyclines, which
decreases water solubility. This is why tetracyclines aren’t taken with milk or vitamins

10. O O
OH
NH2
CH3HO
C
O
OH
OHOH
CH3H3C
N
H3C
CH3
H3C
H
N
O
N
H
CH3H3C
N
O O
OH
NH2
C
OH
OHOH
CH3H3C
N
O
CH3H3C
N
O O
OH
NH2
C
OH
OHOH
CH3H3C
N
O
O O
OH
NH2
C
OHCH2
O
OH
OHOH
CH3H3C
N
N
H3C CH3
OH OH
OH
O
OH
C
HO CH3
NH2
OH
OO
N
H3C CH3
Cl
OH OH
OH
O
CH2 OH
C
NH2
OH
OO
O O
OH
NH2
CH3HO
C
Cl
OOH
OH
OH
CH3H3C
N
O O
OH
NH2
H
C
Cl HO
OOH OH
OH
CH3H3C
N
O O
OH
NH2
C
H3C OHH
OOH OH
OH
CH3H3C
N
121110
9
8
7
6
5
4
3
2
1
MECLOCYCLINE
Meclan
MINOCYCLINE
Arestin, Dynacin,
Vectrin, Minocin
METHACYCLINE
[Rondomycin]
DOXYCYCLINE
Vibramycin, Vibra–Tabs
Doryx, Doxy,
DEMECLOTETRACYCLINE
Declomycin
OXYTETRACYCLINE
Terramycin, (Urobiotic)
CHLORTETRACYCLINE
Aureomycin
TETRACYCLINE
Achrommycin, Sumycin,
Panmycin, Teracap, Tetracyn, Tetralan
TIGECYCLINE
Tygacil™
Structures of important tetracyclines

11. The keto-enol tatomerism
Between c2 and c3 are very
important for biological
activity.
‘D’ ring should be
always aromatic
Changes in this ring
Leads to biological
inactivation of the molecule. Conversion of
corboxamide group to
nitriles cause a 20 fold
loss of activity.
Epimerization at c4
and dehydration at 5a
results loss of activity.
Elimination of 6-OH group
Causes increase lipophilicity
And more stable to acids.
Ex: Doxycycline.
The linearly fused tetracyclic
nucleus is most important
for the antibiotic activity.
Inviolate zone is essential
Little information
available.
Substitution of
-N(CH3)2 at 7
increase the activity.
Ex: Minocycline.
(=CH2 at c6 increases the
Antibacterial activity Ex: Methacycline).
(any modification at
C3 loss of activity.)
Electron donating (or)
electron withdrawing
groups at c7 increased
Antibacterial activity Substitution with –OH Produce
water soluble derivatives which can
be administered orally.
Additional glycyl amino
substitution at the 9th
Position leads to the new
Class of antibiotics
the glycylcyclines.
EX: Tigecycline.(Tygacil)
Presence 0f-N(CH3)2 group at
C4 Tetracyclines exists Ziwitter ion
Which can be posible to distribute in
The body.Removal of this group loss
of activity.
Replacement of –No2 group Gives
more potent but carcinogenic compounds.
ABCD

12. SAR summarization

13. Important structrual units and the three acidity
constants in the tetracycline molecule.
(conjugated
Trione system
Is acidic nature)
(Conjugated phenolic
Enone system is slightly
basic)
Strong alkaline.
pka1 (2.8-3.4)
pka(7.2-7.8)
Pka3 (9.1-9.7)

14. AMPHOTERIC NATURE 3 structural units (3 groups are responsible for the amphoteric
nature of tetracyclines.
Amphoteric nature of tetracyclines:
The tetracyclines are amphoteric compounds.Amphoteric,
meaning they will form salts with both strong acids and bases. Thus,
they may exist as salts of sodium or chloride.
Three structrual units of tetracyclines reprasenting 3pka
values.
Pka1--- Conjugated trione system extending from C1 to C3 of
ring A is acidic nature of Pka 2.8-3.4.
Pka2--- Conjugated phenolic enone system from C10-C12 is
associated with weak basic Pka values ranging from 7.2-
7.8.
Pka3-- C4 atom and its substituents exhibits Pka3 ranging from
9.1 to 9.7. which represents strong alkaline natue.
Because of the amphoteric nature tetracyclines forms
water soluble salts with strong acids such as Hcl and strong
bases such NaOH,KoH.

15. Epimerization
 One of the important property of
tetracyclines is their ability to
undergo epimerisation at C4
position.
 These isomerts are called
epitetracyclines.
 By providing acidic conditions on
long standing about one day
equilibrium can be established
between the isomers.
 Under acidic condition,
tetracycline decline to the
elimination reaction of giving
off H2O from the C-6 hydroxyl
and C-5a hydrogen to
generate the inactive 4-
epitetracyclines.
 These epitetracyclines are less
activie than Natural tetracyclines.
Natural form (more active) (less active
(Or)
inactive

16. Most of the natural tetracyclines have tertiary benzylic hydroxyl group at c-6.
Aromatization of ring C under acidic condition (to prevent zwitterion ion
formation) occurring as a result of dehydration reaction, which is accelerated by
elevated temperatures. The elements of H2O derive from the 6-OH and 5a-H
atom.
6
5a
-H2o
-H2o
(acid)
ABCD
(Napthalene derivative)

17. Base-catalyzed instability of tetracylines
 Under alkaline condition, OH at C-6 change into oxygen
anion and then attacks the C-11 lead to intramolecular
nuclear reaction, by electron transfer, C ring rupture to
generate inactive lactone isomer isotetracycline
 Putting the tetracyclines in a basic solution leads to
cleavage of ring C from ring B, which leads to the
formation of inactive isotetracycline
Isotetracycline
OH-
-H20

19. Chelation
 Chelation is an important feature of the chemical and clinical properties of
the tetracyclines.
 The acidic functions of the tetracyclines are capable of forming salts through
chelation with metal ions.
 Tetracyclines are able to form complexes with divalent and trivalent metal
ions such as Ca2+
,Fe2+
,Mg2+
,Ni2+
,Co2+
,Zn2+
,Mn2+
and Al3+
,Fe3+
.
and with salicylates,phosphates,citrates,polyvinylpyrrolidine,Thiourea,
lipoproteins,serum albumin,globins and RNA.
 These salts of metal ions are insoluble in water at neutral PHs.
 This insolubility not only is inconvenient for the preparation of sloutions but
also interfers with blood levels on oral administration.
 The tetracyclines are incompatible with coadministered,multivalent ion-rich
antacids and with hematinics and concamitant cosumption of daily products
rich in calcium ion also is contraindicated.
 Further the bones,of which the teeth are the most visible, are calcium-rich
struchtures at nearly neutral pHs and so accumulate tetracyclines in
proportion to the amount and duration of therapy when bones and teeth are
being formed.
 Because the tetracyclines are yellow,this leads to a permanent discoloration.

20.  and the teeth are even
brown.(photochemical
process).
 When so much antibiotic is
tanen up that the structure
od bone is mechanically
weakened. To avoid this
tetracyclines are not normally
given to children at the age
of 6 to 12 years.(In severe
cases the teeth can be
treated with dil.Hcl sloution
to dissovle away the colored
antibiotic.Infact it must be
repaired by plastic
impregnation.
 When concomintat oral
therapy with tetracyclines
and incompatable metal

21. Mechanism of action of tetracyclines
 Tetracyclines inhibit protein synthesis by binding to the bacterial ribosome
involved in the translation(protein synthesis) process and making them
bacteriostatic.
 The bacterial ribosome is a 70s particle made up of 30s subunit and 50s
subunit.(the term 50s etc..refer to the sedimentation properties of the
various structures.These are related to the qualitatively to size and mass but
not quantitatively-that’s why a 50s and 30s units combine to form 70s
ribosome).
 The 30s subunit binds mRNA and initiates the protein synthesis.
 The 50s subunit combines with the 30s subunit-mRNA complex to form a
ribisome
then binds aminoacyl tRNA and catalyses the building of the protein chain..
 There are two main binding sites for the tRNA molecule.
 The peptidyl(p-site) binds the tRNA bearing the peptide chain
 The acceptor aminoacyl site (A-site)
 Tetracyclines reversibly bind to the 30S subunit at the A-site to
prevent attachment of the amino acyl tRNA, terminating the
translation process.
 They have excellent selective toxicity due to better binding to the 70 S
subunit in comparison to the 80 S subunit
 . Tetracyclines also show efficient transportation into the bacterial cell. They
enter through porins in Gram negative bacteria and lipophilicity allows them
to enter in Gram positive bacteria.
 Once they have entered through an active transport, the bacteria mistakes
the antibiotic as food.

22. l
(t-RNA interprets the coded
Message in mRNA. It contain
Anticodon of 3-nucleic acid
Bases which binds to triplet
On mRNA.
Tetracycline blocks
.
Tetracyclines blocks or
inhibit(prevent) the
Binding of
Amino acyl t-RNA to the
mRNA ribosomal complex
peptidyl site
(P-site).
(A-site)
Anticodon
Transcription is the process by which
A segemnt of DNA is copied as mRNA.
M-RNA carries the genitic information
required for the synthesis of a protein
from the nucleus to the endoplasmic
called translation. The growing protein
chain is transferred from one t-RNA to the aminoacid on the
next tRNA and
is released once the complete
proten molecule has been synthesized.
Triplet code tobe
Read here.
(aminoacyl)

23. There are two main
Binding sites for t-RNA
Molecule.
The Peptidyl(p-site)binds the
t-RNA bearing the peptide
Chain.
The acceptor aminoacyl site
(A-site) binds the t-RNA
Bearing the next amino acid
to which the peptide chain
Will be transferred.
Peptide transfer
A-site
(p-site)
Tetracyclines works by
slowing the growth of
sensitive bacteria by
interfering with the
production of proteins
needed by the bacteria.
To grow slowing the
bacteria's growth allows
the body's defense
mechanisms to destroy
them.

25. Animation Illustrating the Role of Tetracyclines in Blocking Translation
during Bacterial Protein Synthesis
The tetracyclines (tetracycline, doxycycline, demeclocycline, minocycline, etc.)
block bacterial translation by binding reversibly to the 30S subunit and
distorting(give a misleading account and pullor twist out of shape) it in such a
way that the anticodons of the charged tRNAs cannot align properly with the
codons of the mRNA.

26. Spectrum of activity of tetracyclines
 Tetracyclines are broad spectrum
antibiotics active against
Gram+ve and Gram-ve bacteria
including
1. Staphylococci
2. Streptococci
3. Enterococci
4. Bacillus anthraces
5. Hemophilus influenzae
6. Yersenia pestis
7. Acne vulgaris
8. Shigella species
9. Klebsiella species
10. spirochetes
11.mycoplasmas,
12.rickettsiae,
13.Candida albicans
14.Mycoplasma pneumoniae
15.Chlamydia trachomatis
16.Borrelia recurrentis.
17.Vibrio cholerae
18. Campylabacter fetus
19.Brucella specie
20.Streptococcus
pneumoniee.
21.Neisserie gonorrhoeae
It is used in the treatment of life
threatening infections such as
 Septicemia
 Endocarditis
 meningitis.

27. Toxicity of tetracyclines/Adverse effects of tetracyclines.
 Majour toxic effects of tetracyclines are—
Binding of tetracyclines to the developing bones and teeth and discoloration of teeth
while in development (<8 years of age): accumulation occurs in Calcium rich tissues
such as bones and teeth, which turns the teeth brown via a photochemical process that
is permanent .
(Tetracycline use should be avoided in pregnant or lactating women, and in children with
developing teeth because they may result in permanent staining (dark yellow-gray
teeth with a darker horizontal band that goes across the top and bottom rows of teeth).
 Common side effects associated with tetracyclines include cramps or burning of the
stomach, diarrhea, sore mouth or tongue.
 Tetracyclines can cause skin photosensitivity, which increases the risk of sunburn
under exposure to UV light. This may be of particular importance for those intending to
take doxycyline long-term doxycyline on holidays as a malaria prophylaxis.
 Photosensitivity: exposure to the sunlight results in the formation of free radicals,
especially with a chloride substitution at the 7-position
Rarely, tetracyclines may cause allergic reactions. Very rarely severe headache and
vision problems may be signs of dangerous secondary intracranial hypertension.
These antibiotics should not be used in children under the age of 8, and specifically
during periods of tooth development.
 Tetracyclines are classed as pregnancy category D. Use during pregnancy may cause
alterations in bone development.
 There is little evidence that tetracyclines reduce the efficacy of the birth control pill
unless they cause gastrointestinal upset.

28.  Tetracyclines should be used with caution in those with liver
impairment and may worsen renal failure (except doxycycline and
minocycline).
 Antacids and milk reduce the absoption of tetracyclines. Drugs in
the tetracycline class become toxic over time, so expired
prescriptions of these drugs should be discarded after the
expiration date has passed.
 Administration of expired or degraded tetracyclines may cause
Nausea,vomiting,acidosis,poly urea.
some tetracyclines may cause diabetes insipidus.
In patients suffering with myasthenia gravis tetracyclines may
increase muscle weakness.
In case of liver impairment or liver failure tetracyclines may cause
azotemia(presence of urea excessive amonts ie.nitrogenous wate
materials in the blood.
Tetracyclines cause extremely dry and flaky skin when applied
externally.
The breakdown products of tetracyclines are toxic and can cause
Fanconi syndrome, a potentially fatal disease affecting proximal
tubular function in the nephrons of the kidney.

29. Uses of tetracyclines
 Tetracyclines are called "broad-spectrum" antibiotics, because
they can be used to treat a wide variety of infections.
 Physicians may prescribe these drugs to treat eye infections
 Tetracyclines are generally a low-cost alternative among
antibiotics.
 Interestingly, a form of tetracycline has recently been used in
prevention of cancer recurrence
 They inhibit certain enzymes and processes that normally
encourage cancer growth. By making cancer cells less
aggressive, these drugs may show potential for long-term
management of some cancers.
 Syphilis.
 Tetracyclines may be used in the treatment of infections of
the respiratory tract, sinuses, middle ear, intestines.
 Gonorrhoea

30.  Acne Rosacea
 Acne vulgaris
 Actinomyces Israelii
 Actinomycosis
 Anthrax
 Bacillus Anthracis
 Bacterial Conjunctivitis
 Balantidium coli
 Bartonella Bacilliformis
 Bartonellosis
 Bordetella Pertussis
 Borrelia Burgdorferi
 Borrelia Recurrentis
 Bronchitis- acute
 Brucella Sp.
 Brucellosis
 Burkholderia Mallei
 Burkholderia
Pseudomallei
 Campylobacter Fetus
 Cervicitis
 Chancroid
 Chlamydia Psittaci
 Chlamydia Trachomatis
 Chlamydial Conjunctivitis
 Chlamydia Trachomatis
 Chlamydial Conjunctivitis
 Clostridium Tetani
 Coxiella Burnetii

31.  Duodenal Ulcer
 Entamoeba
Histolytica
 Francisella Tularensis
 Fusobacterium Fusiforme
 Gonorrhea
 Granuloma Inguinale
 Haemophilus Ducreyi
 Haemophilus Influenzae (beta-
lactamase Negative)
 Haemophilus Influenzae (beta-
lactamase Positive)
 Helicobacter Pylori
 Klebsiella Granulomatis
 Legionella Pneumophila
 Leptospira Sp.
 Leptotrichia Buccalis
 Listeria Monocytogenes
 Lower Respiratory Tract
Infections
 Listeria Monocytogenes
 Lower Respiratory Tract
Infections
 Lower Respiratory Tract
Infections
 Listeria Monocytogenes
 Lower Respiratory Tract
Infections
 Lymphogranuloma Venereum
 Murine Typhus
 Mycobacterium Fortuitum
 Mycoplasma Hominis
 Mycoplasma Pneumoniae
 Neisseria Gonorrhoeae
 Neisseria Meningitidis
 Nocardia Sp.
 Non-gonococcal Urethritis (NGU)
 Ophthalmia Neonatorum
Prophylaxis
 Otitis Media
 Pasteurella Multocida
 Periodontitis
 Pharyngitis

32.  Plague
 Plague Prophylaxis
 Plasmodium Falciparum
 Pneumonia
 Proctitis
 Propionibacterium Acnes
 Propionibacterium Propionicum
 Psittacosis
 Q Fever
 Relapsing Fever
 Rickettsia Akari
 Rickettsia Prowazekii
 Rickettsia Rickettsii
 Rickettsia Tsutsugamushi
 Rickettsial Pox
 Rocky Mountain Spotted Fever
 Shigella Sp.
 Shigellosis
 Sinusitis
 Skin And Skin Structure Infections
 The tetracyclines will not work for
colds, flu, and other infections caused
by viruses
 Spirillum Minus
 Streptobacillus Moniliformis
 Syphilis
 Treponema Pallidum
 Tularemia
 Upper Respiratory Tract Infection
 Ureaplasma Urealyticum
 Urinary Tract Infection
 Vibrio Parahaemolyticus
 Yaws
 Yersinia Enterocolitica
 Yersinia Pestis
 Amebiasis
 Anthrax Prophylaxis
 Bejel
 Biliary Tract Infections
 Cholera
 Dentoalveolar Infection
 Dyspepsia
 Endodontic Infection
 Enterocolitis
 Gastric Ulcer
 Legionnaire's Disease
 Lyme Disease
 Malaria
 Pinta
 Tertiary Syphilis

33. Cautions, contraindications, side-effects
Are as those of the tetracycline antibiotics group:
Can stain developing teeth (even when taken by the mother during pregnancy)
Can cause permanent teeth discoloration (yellow-gray-brown); infancy and childhood
to eight (8) years old
Inactivated by Ca2+ ion, not to be taken with milk, yogurt, and other dairy products
Inactivated by aluminium, iron and zinc, not to be taken at the same time as indigestion
remedies
Inactivated by common antacids and over-the-counter heartburn medicines.
Skin photosensitivity; exposure to the Sun or intense light is not recommended
Drug-induced lupus, and hepatitis
Can induce microvesicular fatty liver.
Tinnitus
May interfere with methotrexate by displacing it from the various protein binding sites
Can cause breathing complications as well as anaphylactic shock in some individuals
Should be avoided during pregnancy as it may affect bone growth of fetus.
Passes into breast milk and is harmful to breast-fed infants, and should therefore be
avoided during breastfeeding if possible.

34. The Future of Tetracyclines:
The future of tetracyclines looks promising in respect to decreasing
resistance, due to the addition of substituents at the 9-position. Newer
agents with less side effects and an increased spectrum of activity are
currently being studied to increase popularity in treatment using
tetracyclines. Two new agents that are being studied are 9-
nitromethyldeoxytetracycline and 9-nitrominocycline which are
glycylcyclines. They look to promise treatment of infections caused by
bacteria resistant to previous tetracyclines.3

35.  Tetracyclines should therefore be
avoided in pregnant or lactating
women, and in young children
with developing teeth. A pregnant
woman who takes tetracycline
might cause stains to the
deciduous teeth of her baby. A
child who takes tetracycline might
cause stains to his developing
adult teeth. Those stains are
usually internal and cannot be
easily removed with conventional
tooth whitening. It is therefore
recommended not to give
tetracycline to children under 12
years of age. They are however
safe to use in the first 18 weeks
of pregnancy.
 Even though tetracyclines cause
tooth discolouration for only
developing teeth, they are
considered very safe for adults,
including women who are not
pregnant. The tetracycline group
is the only family of antibiotics
that can stain developing teeth.
All other antibiotics are not

36.  Tetracycline can
cause skin
reaction(fixed durg
eruptions)
Skin lesions

37. What are the possible side effects of Tetracycline?
 Get emergency medical help if you have any of these signs of an
allergic reaction: hives; difficulty breathing; swelling of your face,
lips, tongue, or throat.
 Stop using tetracycline and call your doctor at once if you have any
of these serious side effects:
 severe headache, dizziness, blurred vision
 fever, chills, body aches, flu symptoms
 severe blistering, peeling, and red skin rash
 urinating less than usual or not at all
 pale or yellowed skin, dark colored urine, fever, confusion or
weakness
 severe pain in your upper stomach spreading to your back, nausea
and vomiting, fast heart rate
 loss of appetite, jaundice (yellowing of the skin or eyes); or
 easy bruising or bleeding, unusual weakness
 Less serious side effects may include:
 sores or swelling in your rectal or genital area
 mild nausea, vomiting, diarrhea, or stomach upset
 white patches or sores inside your mouth or on your lips
 swollen tongue, trouble swallowing; or

38. What other drugs affect Tetracycline?
 Before taking tetracycline, tell your doctor if you are taking
any of the following drugs:
 cholesterol-lowering medications such as cholestyramine
(Prevalite, Questran) or colestipol (Colestid)
 isotretinoin (Accutane)
 tretinoin (Renova, Retin-A, Vesanoid)
 an antacid such as Tums, Rolaids, Milk of Magnesia, Maalox,
and others
 a product that contains bismuth subsalicylate such as Pepto-
Bismol
 minerals such as iron, zinc, calcium, magnesium, and over-
the-counter vitamin and mineral supplements
 a blood thinner such as warfarin (Coumadin); or
 a penicillin antibiotic such as amoxicillin (Amoxil, Trimox,
others), penicillin (BeePen-VK, Pen-Vee K, Veetids, others),
dicloxacillin (Dynapen), carbenicillin (Geocillin), oxacillin
(Bactocill), and others

39. What warnings do you have for
Tetracycline?
 The following warnings are available for this
medication:
 Finish the prescription.
 Take on empty stomach.
 Take with plenty of water.
 Shake well.
 Do not take with milk, antacids, or iron.
 Avoid exposure to sun.
 Do not take if pregnant

40.  What is the most important information I should know
about Tetracycline?
 Do not use this medication if you are pregnant. It could
cause harm to the unborn baby, including permanent
discoloration of the teeth later in life. Tetracycline can
make birth control pills less effective. Use a second
method of birth control while you are taking tetracycline
to keep from getting pregnant.
 Tetracycline passes into breast milk and may affect bone
and tooth development in a nursing baby. Do not take
this medication without telling your doctor if you are
breast-feeding a baby.
 Do not give tetracycline to a child younger than 8 years
old. Tetracycline can cause permanent yellowing or
graying of the teeth, and it can affect a child's growth.
 Avoid exposure to sunlight or artificial UV rays
(sunlamps or tanning beds). Tetracycline can make your
skin more sensitive to sunlight and sunburn may result.
Use a sunscreen (minimum SPF 15) and wear protective
clothing if you must be out in the sun.
 Do not take iron supplements, multivitamins, calcium
supplements, antacids, or laxatives within 2 hours
before or after taking tetracycline. These products can
make tetracycline less effective.
 Throw away any unused tetracycline when it expires or
when it is no longer needed. Do not take any
tetracycline after the expiration date on the label has
passed. Expired tetracycline can cause a dangerous
syndrome resulting in damage to the kidneys